The present invention relates to liquid filters, particularly for water irrigation systems, however also useful for other industrial or domestic applications.
More specifically, the invention concerns filter devices of the type disclosed in our U.S. Pat. No. 4,655,910 issued Apr. 7, 1987, the contents of which is hereby incorporated by reference (hereinafter called xe2x80x9cthe Patentxe2x80x9d).
The Patent has introduced for the first time the concept of using filter devicesxe2x80x94in particular of the type utilizing a battery of filter discsxe2x80x94with reverse flushing water flow cycles wherein the discs were caused to spin under the impact of water jets impinging thereon (hereinafter referred to as xe2x80x9cSpin-Clean Filtersxe2x80x9d).
The various constructional examples disclosed in the Patent had in common a centrally extending conduit serving the dual function of leading the flushing water to a series of nozzles provided thereon, and of supporting the spinning movement of the discs.
This feature of construction presented, however, certain disadvantages: the operation of the hydraulic cylinder system, responsible for relieving the pack of discs from the compact, filtering position, was mainly dependent upon the level of back-pressure applied by the reverse water flow, dictated, among others, by a relatively large diameter piston; rather cumbersome valve means had to be used for directing the reverse flow of water into the nozzled conduit; and generallyxe2x80x94an excessive number of parts and components had to be used, causing respective increase of the manufacture, assembly and maintenance costs of the product.
It is thus the general object of the present invention to overcome the above-listed deficiencies of the conventional spin-clean filters.
It is a further object of the invention to simplify the design of the spin-clean filters, by providing a core member of the filter device of a unitary and integral construction, readily produced by plastics injection molding process, that will effectively serve the combined functions of:
generating the water jets;
supporting the revolving movement of the filter discs (or integral filter member of different types such as screen filters);
providing convenient access to the hydraulic piston assembly by external pressure control means;
forming a seat for a simple, elastic sleeve-type valve member responsive to the oppositely directed water flows during the filtering and the flushing modes of operation, respectively; and
providing a centrally extending tube through which pressure commands are admitted for the operation of the hydraulic piston, controlling the disengagement of the filter discs.
It is a still further object of the invention to provide a filter device with one or more jets generating conduits which extend off-centrally relatively to the axis of the filter member, along and adjacent to a generatrix line thereof.
It is a still further object of the present invention to provide a ribbed structure for supporting the spinning motion of the filter element(s) independently of jet generating conduit(s).
It is therefore proposed according to the present invention to provide a liquid filtering device, particularly for irrigation water installations of the type comprising a cylindrical housing with an inlet port and an outlet port and a cylindrical filter member installed within the housing so that water flowing from the inlet to the outlet enters the filter member in a radial direction, and discharged through the outlet port, and vice-versa during a reversed, filter flushing flow cycles, the device comprising a filter core member centrally mounted within the cylindrical space defined by the filter member, the core member comprising at least one tubular conduit extending within, adjacent to, and along a generatrix line of the filter member, the conduit being closed at one end and in free communication with the outlet port through its other end; a series of nozzles associated with the conduit so that water under pressure within the conduit becomes discharged in jet forms and a filter support structure configured to enable free rotation of the filter member therearound; one-way valve means adapted to allow the flow of filtered water from the filter member to the outlet port but to impede the flow of flushing water from the outlet through the filter in the reverse direction; a fixed member at one side, and a displaceable member at the other side of the filter member; means for urging the displaceable member against the filter member to clamp same between the displaceable and the fixed members; hydraulic activating means associated with the displaceable member and external controllable pressure means operatively coupled to the displaceable member, the arrangement being such that upon a pressure command by the pressure means, the displaceable member is moved away from the filter member to relieve the clamping engagement thereof, and upon application of the filter flushing flow the water jets are sprayed to rinse the filter member.
According to a preferred embodiment of the invention, the filter core member is integrally formed by plastics injection molding process.